MAGNETIC-FIELD-INDUCED PAIR-BREAKING EFFECTS IN GRANULAR PB FILMS NEAR THE SUPERCONDUCTOR-TO-INSULATOR TRANSITION

We have measured the magnetic-field dependence, 0 less-than-or-equal-t o- H less-than-or-equal-to 8 T, of the resistive transitions R (T) of ultrathin granular superconducting Pb films with normal-state sheet re sistances, R(Q) less-than-or-equal-to R(N) less-than-or-equal-to 100 k OMEGA, where R(Q) = h/4e2 congruent-to 6.45 kOMEGA. The data suggest t hat the magnetic-field-induced superconductor-to-insulator transition in these films occurs in a field regime where pair-breaking effects ha ve significantly reduced the amplitude of the superconducting order pa rameter. We compare our results with those obtained on systems with un iform morphologies.